PURPOSE: To eliminate the need of a battery on the key side by attaching to the key a transceiver circuit which is resonant with electromagnetic waves and providing on the lock side an oscillator which oscillates electromagnetic waves when the key approaches and a control device which detects these electromagnetic waves.

CONSTITUTION: An electric lock system is composed of a lock device 1, a coil 12 attached to the door, an oscillator 11, a control device 5, and a controlled section 3 which opens or closes the lock device 1. In addition, a transceiver 2 which is resonant with electromagnetic waves is attached to the key. Then, when the key approaches the lock device 1 the oscillator 11 oscillates intermittently due to magnetic field mutual induction and thus an electric current flows through the coil 12. This in turn causes the control device 5 to sense the approaching key and an instruction to release the lock is given to controlled section 3 which opens or closes the lock device 1. This eliminates the need of a battery in the transceiver circuit 2 of the key and allows the structure to be simpler and more compact.